1. Field of the Invention
The present invention relates to a packaging bag that can be reopened and reclosed, and a method for manufacturing such a reclosable packaging bag.
2. Description of the Related Art
A reclosable packaging bag 1, which has conventionally been used, comprises a main bag body 7 and a linear fastener 9 as shown in FIG. 25. The main bag body 7 is formed by placing two sheets of plastic film material 2, 3 one upon another and heat-sealing the opposite side edges and the lower edge of them so that the main bag body 7 has an upper opening portion 8 and heat-sealed portions 4, 5, 6. The linear fastener 9 is provided on the inner surface of the opening portion 8 of the main bag body 7. The opening edge of the reclosable packaging bag 1 is closed by subjecting the opening edge to a heat sealing process after filling the bag 1 with the contents. The linear fastener 9 is composed of a fastening member having a male-engaging portion and the other fastening member having a female-engaging portion.
With respect to the manufacturing method of the above-mentioned reclosable packaging bag, the linear fastener 9 is cut off to a length, which is identical to the width of the sheets of plastic film material 2, 3, in order to provide the main bag body 7 with the linear fastener 9. The one fastening member of the linear fastener 9 thus cut is temporarily bonded on the inner surface of the one edge of the sheet 2. The other fastening member of the linear fastener 9 thus cut is temporarily bonded on the inner surface of the one edge of the sheet 3. The heat-sealing process, which is applied to the sheets 2, 3 to form the main bag body 7, causes the fastening members of the linear fastener 9 to be secured firmly on the inner surface of the main bag body 7.
In the above-mentioned conventional reclosable packaging bag, the linear fastener 9 extends continuously from the outer edge of the heat-sealed portion locating on the one side of the main bag body to the outer edge of the heat-sealed portion locating on the other side of the main bag body. Consequently, each of both side portions of the main bag body has a thickness, which is identical to the total of the thickness of the two sheets and the thickness of the fastening members. There is required enough pressure and quantity of heat by which the fastening members can be melted and deformed, when applying the heat-sealing process to the opposite sides of the main bag body. A required period of time for the heat-sealing process is therefore extended.
The step for cutting off the linear fastener to the length, which is identical to the width of the sheets of plastic film material, and the step for bonding the fastening members for the linear fastener on the inner surfaces of the sheets of plastic film material are essential to the method for manufacturing the above-mentioned reclosable packaging bag. Improvement in processing efficiency may be restricted.
In general, the reclosable packaging bag has so small rigidity that the reclosable packaging bags receiving the contents cannot be exhibited as merchandise in a stacked state.